Add support for staggerd column layout KB "Fortitude60" (#3090)

* modifying fortitude for working

* add accurate keymap

* backlight fix

* Fix slave LED Backlight

* Add readme.md

* modified readme.md

* Fixed make error

* Commit including suggestions

* Add dvorak and colemak layout and some fix

keyboards/fortitude60/serial.h

@@ -0,0 +1,32 @@
+#ifndef MY_SERIAL_H
+#define MY_SERIAL_H
+
+#include "config.h"
+#include <stdbool.h>
+
+/* TODO:  some defines for interrupt setup */
+#define SERIAL_PIN_DDR DDRD
+#define SERIAL_PIN_PORT PORTD
+#define SERIAL_PIN_INPUT PIND
+
+#ifndef USE_SERIAL_PD2
+#define SERIAL_PIN_MASK _BV(PD0)
+#define SERIAL_PIN_INTERRUPT INT0_vect
+#else
+#define SERIAL_PIN_MASK _BV(PD2)
+#define SERIAL_PIN_INTERRUPT INT2_vect
+#endif
+
+#define SERIAL_SLAVE_BUFFER_LENGTH MATRIX_ROWS/2
+#define SERIAL_MASTER_BUFFER_LENGTH 1
+
+// Buffers for master - slave communication
+extern volatile uint8_t serial_slave_buffer[SERIAL_SLAVE_BUFFER_LENGTH];
+extern volatile uint8_t serial_master_buffer[SERIAL_MASTER_BUFFER_LENGTH];
+
+void serial_master_init(void);
+void serial_slave_init(void);
+int serial_update_buffers(void);
+bool serial_slave_data_corrupt(void);
+
+#endif